California earthquakes

M2.8 earthquake 2km NNE of Calimesa, CA

A magnitude 2.8 earthquake struck 2km NNE of Calimesa, CA on Sat, Dec 9, 1939, 10:46 AM GMT-8 (18:46 UTC), 22 km (13 mi) below the surface.

A larger quake followed: M3.1 4km SSW of Yorba Linda, CA. This one was a foreshock.

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Map

Where this earthquake was located, with the others nearby. Select one for its page.

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The earthquake

Magnitude
2.8 (ml), micro
Local time
UTC
1939-12-09 18:46:39 UTC
Depth
21.6 km (13.4 mi), shallow
Epicenter
34.009° N, 117.043° W
Tsunami flag
No
Status
Reviewed by a seismologist

Did you feel it?

No one has reported feeling this quake to the USGS.

How well it is located

Reviewed by a seismologist.

Location uncertainty
About 7.7 km horizontally, 4.5 km in depth
Magnitude uncertainty
±0.43
Depth from
From location
Station coverage gap
241°, poorly surrounded by stations
Stations used
4

Nearest places

Distance and direction from each place to the epicenter, with its forecast.

Nearby

Within 100 km, magnitude 1.5 and up: 8 in the 60 days after this one and 5 in the 30 days before it.

After

Before

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Sources

From the USGS Earthquake Hazards Program and its partner networks, event ci3365166. Read Tue, Sep 22, 2026, 8:24 PM UTC.